We introduce DMET, a new quantum embedding theory for predicting ground-state
properties of infinite systems. Like dynamical mean-field theory (DMFT), DMET
maps the the bulk interacting system to a simpler impurity model and is exact
in the non-interacting and atomic limits. Unlike DMFT, DMET is formulated in
terms of the frequency-independent local density matrix, rather than the local
Green's function. In addition, it features a finite, algebraically
constructible bath of only one bath site per impurity site, which exactly
embeds ground-states at a mean-field level with no bath discretization error.
Frequency independence and the minimal bath make DMET a computationally simple
and very efficient method. We test the theory in the 1D and 2D Hubbard models
at and away from half-filling, and we find that compared to benchmark data,
total energies, correlation functions, and paramagnetic metal-insulator
transitions are well reproduced, at a tiny computational cost.Comment: 5 pages, 5 figure
